class_docstr: LexRank: Graph-based Centrality as Salience in Text Summarization
  Source: http://tangra.si.umich.edu/~radev/lexrank/lexrank.pdf
class_docstr_tok: ["LexRank",":","Graph-based","Centrality","as","Salience","in","Text","Summarization","Source",":","http",":","\/\/tangra.si.umich.edu\/~radev\/lexrank\/lexrank.pdf"]
code: def _ensure_dependencies_installed():
      if numpy is None:
          raise ValueError(
              "LexRank summarizer requires NumPy. Please, install it by command 'pip install numpy'."
          )
  
file_path: sumy/sumy/summarizers/lex_rank.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  import math
  from collections import Counter
  from ._summarizer import AbstractSummarizer
label_desc: Use image node_id 4 for calling the LexRankSummarizer obj's underlying member method code with example usage: obj._ensure_dependencies_installed() without return types